Energy 2: Acetyl Coenzyme A, Mitochondrial, Oxygen Flashcards
What does TCA stand for?
Tricarboxylic acid cycle
When and where does aerobic respiration happen?
In the presence of oxygen, in mitochondria
What is the output of the TCA cycle?
8 NADH
2 FADH2
2 GTP
6 CO2
Where does the TCA cycle take place?
In the mitochondrial matrix
What is pyruvate converted to in the TCA cycle?
Acetyl coA
What does acetyl CoA react with to form citrate?
Oxaloacetic acid
What regulates entry into the TCA cycle?
Formation of acetyl coA from pyruvate is irreversible. Commits the glucose carbon skeleton to either oxidation to CO2 or fatty acid synthesis
What is the enzyme involved in regulation of entry into the TCA cycle?
Pyruvate dehydrogenase
What is pyruvate dehydrogenase inhibited by?
Inhibited by NADH, ATP and acetyl coA
What other two enzymes are involved in regulation of the TCA cycle (not pyruvate dehydrogenase)?
Kinase and phosphatase
In muscle, what is pyruvate hydrogenase phosphatase stimulated by?
Ca2+
In the liver, how does adrenaline increase Ca2+?
Through the stimulation of alpha adrenergic receptors and IP3
What does insulin stimulate in liver and adipose tissues?
Phosphatase which funnels glucose to fatty acid synthesis
What is pyruvate dehydrogenase stimulated by?
ADP pyruvate
What is citrate synthase inhibited by?
Citrate
What is isocitrate dehydrogenase inhibited by?
NADH, ATP
What is isocitrate dehydrogenase stimulated by?
ADP
What is alpha-ketoglutarate dehydrogenase inhibited by?
NADH, ATP, succinyl CoA
What is beri beri and where is it common?
A deficiency in thiamine (vitamin B1), common where rice is a staple
What is beri beri characterised by?
Cardiac and neurological symptoms
What is thymine a prosthetic group for?
Pyruvate and alpha-ketoglutarate dehydrogenase
What happens to the NADH and the FADH2 produced in the TCA cycle?
They donate hydrogen atoms to complexes where the atom is split into proton and electrons
What happens to the electrons produced by the breakdown of hydrogen in the mitochondria after the TCA cycle?
Transported through the cytochromes (final acceptor is oxygen which is then used to generate water)
How many ATP molecules does NADH and FADH2 form in oxidative phosphorylation ?
NADH forms 3, FADH2 forms 2
How many protons does NADH and FADH2 pump out in oxidative phosphorylation ?
10 for each NADH
6 for each FADH2
Give the steps in ATP synthesis
As electrons are passed down the ETC protons are pumped from the mitochondrial matrix into the intermembrane space, which forms an electrochemical gradient.
The gradient is dissipated by the passage of protons through ATP synthase, which forms ATP
How much (lots or not much) mitochondria is there in brown fat?
Lots
Where is brown fat found in babies?
The shoulder/neck area
What is brown fat used for?
To generate heat for as a newborn
What protein do brown fat mitochondrial inner membranes contain?
Uncoupling protein 1 (UCP1)
What does UCP1 do?
Diverts the flow of protons away from the generation of ATP and through to the generation of heat. (Proton gradient is dissipated but not in the same way)
What are OXPHOS diseases?
Common degenerative diseases
What are OXPHOS diseases caused by?
Mutations in genes encoding ETC proteins
What are the symptoms in OXPHOS diseases caused by and when do they appear?
Fatigue, epilepsy, dementia
Dependant on the mutation, symptoms may be evident near birth early to early adulthood
What is congenital lactic acidosis?
Can’t make ATP through ETC do have to do it through the conversion of pyruvate to lactate
